Chris,
I used an RRS pump with my RRS pws kit. Expensive at about $700 but well worth it. The problem with the old pump is that they don’t put out consistent pressure, which means your steering won’t be smooth. Just not up the task.
The only thing I don’t like about the RRS pump is the cheap Ford style reservoir. I replaced it with a nice Aeroflow polished aluminium reservoir. You could also try finding a pump with a built in reservoir, similar to GM ones.
When I get a chance, will post a pic of my setup.
Colin